Problem: In 39 years, Stephanie will be 4 times as old as she is right now. How old is she right now?
We can use the given information to write down an equation about Stephanie's age. Let Stephanie's age be $s$ In 39 years, she will be $s + 39$ years old. At that time, she will also be $4 s$ years old. Writing this information as an equation, we get: $s + 39 = 4 s$ Solving for $s$ , we get: $3 s = 39$ $s = 13$.